The present invention relates to a knee support element for motor vehicles or absorbing energy in the knee region in case of a crash of the vehicle.
Knee support element according to the present invention is positioned between a support element of a motor vehicle and an element such as the instrument panel facing the cabin of the motor vehicle.
The knee support element is typically positioned in between the cross car beam (CCB) and the instrument panel (IP) of a vehicle.
During a frontal crash of a car, in case the driver and/or the passenger sitting next to the driver, are not wearing a safety belt, the knees region absorbs an important amount of energy. During the crash the knees will move towards the instrument panel and have an impact on the instrument panel. Underneath the instrument panel energy absorbing brackets will be present to absorb the energy of the incoming knees.
Regulations according to the energy absorption of the instrument panel and the underlying brackets can be found for unbelted dummies in the American standards USFMVSS208.
There are a wide range of possible knee contact points with the instrument panel as well as different knee impacts directions which needs to be covered by using appropriate support brackets. In the prior art it is customary to work with dummies with different sizes. The energy absorbing brackets should be capable of absorbing a sufficient amount of energy in case of a frontal crash with any unbelted dummy.
In the present text, references will be made to different dummies being the 5%, 50% and 95% dummy. The 5% dummy represents relatively small driver. The knees of the unbelted dummy will have impact on a relatively low point of the instrument panel. The 50% dummy represents an average driver. The 50% dummy represents an impact of the mid section of the instrument panel. A 95% dummy represents a relatively tall driver. The 95% dummy will have an impact on a relatively high part of the instrument panel. The brackets should be adapted to ensure that the forces and the moments which occur in the femur and the tibia of a driver during impact are not allowed to exceed a certain value. These values are limited by European, US, Japanese and comparable safety regulations and norms.
In the prior art a knee support for a motor vehicle is known with a cross section which resembles a L. These brackets are known from the American patent application US2003/0057692 (Horsch et al.).
The knee support according to the prior art is positioned in order to have the relatively long part of the L connected to the CCB wherein this long part faces in is directed towards the passenger cabin. The smaller leg of the L points downwards. The bracket according to the prior art is positioned in order to have the connection between the two legs of L in the 50% dummy region. That means that upon impact of a 50% dummy an optimal absorption of energy is possible. As shown in FIG. 5 of US2003/0057692 in the mid section the brackets are only connected to the CCB with the relatively long part of the L. This means that the bracket is not suitable of absorbing a relatively large amount of energy upon impact of a 5% dummy. The bigger the size of the car, thereby the longer the leg of the L facing downward, the more difficult it will be to ensure upon impact a high energy absorption of the 5% dummy.